Subject: Thermal compound application
By: Purfus (IP: 207.5.141.*)
Written on: 04-11-2006 16:38
I just wanted to point out that CPU manufacturers generally recomend applying a thermal compound differently than this guide instructs. This is even more important when using metal based compounds. Instead of applying the compound with your finger (a big no no due to the likelyhood of contaminating the compound) you should apply a small dot of the compound to the center of the CPU core. Keep your fingers out of the compound and the core. Press the heatsink down on the core using firm even pressure. DO NOT allow the heatsink to lift up from the core once contact is made. The reason for this method is to avoid trapping air between the sink and the core, which will often happen if you apply the compound as a thin layer. The pressure from the new mounting systems used on athlon/pent3 or better chips is more than enough to spread the compound appropriatly and leave you with a thin effective layer of compound.
Thermal compounds might be a bit messy if your that kind of person but they have a lot of advantages over pads. I always wash off any preapplied compounds from heatsinks. 99% of the time these pre-applied compounds, pads or otherwise, are cheap materials and made for flexibility and safety not performance. By wash I mean use a solvant and lint free rags until you can detect no traces of the compound on the metal surface. Once that is done and the solvent residues have been removed I will take a dab of arctic silver and another lint free rag and polish the surface of the heatsink. Well polish isn't quite correct altho the surface will usually shine better afterwards. What actually happens is the silver particles in the compound will settle into the crevices of the heatsink surface (there are always pocks and pours on a heatsink surface that can be filled in this way no matter how perfect the finish). This also helps to prevent air molecules from becoming trapped in the crevices. I can't quantitatively tell you what performance benefits there are to these methods but they work great for me and many others.
If you really want a good surface contact try welding the heatsink to the core. Well no don't try it because I'm sure you would kill your CPU in the process but if you could do it without burning the core (depends on your skills and bravery) this would be ideal. However, it is unlikely this will ever be a safe method. For now we'll have to stick with high pressures and high heat capacity transfer mediums.
You should also be carefull with metal based compounds such as arctic silver when dealing with CPU's similar to the earlly athlon chips. These chips have exposed contact points used for configuration of the core's parameters such as clock multiplier. Metal based thermal compounds are conductive and can short connections. Theres enough ways to kill a properly installed chip, theres no need to kill them before you get to play.
Good luck and dont forget to take your fuzzy slippers off and ground your wrist out when handling the chips. And don't plug the system in before installing sensitive components as this will just give static a reason to travel threw the PC instead of threw the ground wire which is hopefully attached to your wrist as close to the component you are handling as posible and hopefully you also keep this ground point on your body lower than the component you are handling.